Primary Schools: Solar panels for schools

Why a primary school is a different solar project

A primary school sits at the smaller, more constrained end of the school-solar spectrum, and pretending otherwise is how installers get primary projects wrong. A typical UK primary is a single-storey building with 200 to 550 square metres of usable roof, and the systems we design for them run 30 to 80 kW using roughly 55 to 150 panels. That is enough to generate 27,000 to 73,000 kWh a year and displace 6 to 17 tonnes of CO2 annually — real money against a bill that has risen 60 to 120 per cent since 2021 while the National Funding Formula has stood still.

The defining feature of a primary is not its size, though — it is its occupancy pattern, and no other school type feels it as sharply. A primary is a term-time-only building with roughly 190 teaching days a year, little evening or weekend use, and a six-week summer shutdown that lands in July and August — the exact weeks your roof generates the most. Size a system off roof area alone and a primary will self-consume only 35 to 55 per cent of what it produces. Everything about designing a good primary system is about closing that gap honestly rather than hiding it. A generalist installer sizes a primary the way they would size a warehouse, off the roof; a schools specialist sizes it off the demand curve, which for a primary is the single most misunderstood number in the quote.

The summer self-consumption problem, in plain terms

Here is the paradox stated bluntly. A solar array on a primary generates its biggest daily output in July and August, when the building is locked, the kitchens are cold and the corridors are empty. It generates its second-biggest output on weekends, when almost nobody is in. During term time the match is genuinely good — peak demand runs 8am to 4pm, which lines up neatly with the middle of the solar day — but term time is only 190 days, and the six-week summer break carves out the sunniest weeks of the year. That is why a naive primary design self-consumes so little, and why the honest answer is not to pretend the export away but to plan for it. There are three levers: a small battery to time-shift the surplus, the Smart Export Guarantee to monetise what is left, and interest-free Salix finance so the project pays regardless. On a primary, all three usually feature in the recommendation.

Typical sizing and the single-phase constraint

Most primaries fall into the £35,000 to £90,000 band with a payback around seven years. But there is a constraint specific to primaries that a generalist installer routinely misses: the electrical supply. A large number of older primary schools are on a 60 to 100 amp single-phase supply, which caps practical PV at roughly 13 to 17 kW per phase before you either trigger a G99 grid application or need a three-phase upgrade from the network operator. That is a genuine niche constraint. It means the difference between a £4,000 quote and a £30,000 quote can come down to whether the school already has three-phase power, and it is why we insist on confirming the incoming supply before we cost anything. Where a three-phase upgrade is needed we build it into the feasibility study rather than springing it on the School Business Manager after the order is placed.

Because most primaries sit comfortably below 100 kW, grid connection is usually straightforward. Systems under 17 kW per phase connect quickly under G98; anything above needs a G99 application to the local Distribution Network Operator, which we submit end to end. The average primary SBM has never dealt with a DNO and should not have to start now — we run the whole grid process from application to commissioning notice.

Why the battery question matters most here

Because the summer self-consumption problem bites hardest at a primary, this is the school type where a small battery most often earns its place. A 50 to 100 kWh battery shifts holiday and weekend generation into term-time use, lifting self-consumption from the low-40s into the 60s or beyond. It is not always the right answer — for a very small array on a school with a tight capital budget, exporting the summer surplus under the Smart Export Guarantee at 4 to 15p/kWh may be the cleaner economics. The point is that on a primary, the battery question has to be modelled from real data, not assumed away. We run both the battery and battery-free cases from your half-hourly meter readings and show you which wins on your building, rather than defaulting to whichever suits the sale.

A worked example

Consider a community primary of around 240 pupils in a single-storey 1970s building, with electricity costs that have climbed from roughly £14,000 to £29,000 in three years. A 55 kW system of about 102 panels, paired with a 75 kWh battery, generates in the region of 50,000 kWh a year and saves around £11,500 annually — a payback near seven years. Funded through an interest-free Salix Decarbonisation Loan, the repayment is set below the annual saving, so the project runs cash-flow positive from year one even before the loan is cleared. The battery is what makes the summer generation count: instead of exporting a July surplus into an empty building's meter for a few pence, the school banks it and draws it down when term restarts in September. In this instance the governing body also wrote the system's live data into the Year 5 Design & Technology scheme of work, so the estates decision became a curriculum one too.

The funding route that fits a primary

For a maintained primary or a primary academy, the default and best-fit route is almost always the Salix Decarbonisation Loan: interest-free, repaid from the energy savings, structured so the project is cash-flow positive from day one. Salix typically lends £20,000 to £400,000 per project over up to eight years — a range that covers essentially every primary install. Where a capital grant is a better fit, the Public Sector Decarbonisation Scheme can fund up to 100 per cent of eligible measures, and academies and voluntary-aided primaries can bid into the Condition Improvement Fund, which scores well when solar is paired with a roof refurbishment. We write the auditable energy-savings calculation these schemes require so the SBM signs the form rather than builds the model. If your primary is a voluntary-aided church school, your diocese will also need to approve material works to the building, and we factor that approval into the timeline. See the full breakdown on our grants and funding page.

Safeguarding, scheduling and access

Nowhere is safeguarding scrutiny higher than in a primary, and it is the single biggest reason to use a specialist. Every operative who enters the site is DBS-cleared to Enhanced level including the Children's Barred List, refreshed annually, and we work to KCSIE 2025 standards throughout: SBM site induction, escorted access in pupil areas, and signed-in/signed-out tracking. Because term-time access to a working primary is often impossible around young children, the disruptive phases — scaffold, roof access, panel transport — are scheduled into the school holidays, with final commissioning handled on an INSET day or a Friday-evening switchover. Most pre-2000 primaries also need an asbestos (ACM) management survey and a structural check before work starts; both are part of our feasibility process rather than a surprise on day one. Most primary buildings are permitted development under Class A, Part 14 of the GPDO 2015, so the majority need no planning application at all — the exceptions are listed board schools and conservation-area sites, which we flag at feasibility.

Turning the roof into a teaching resource

Primaries get more from the curriculum angle than any other school type, because a live, visible energy story lands so well with Key Stage 2 pupils. Most of our primary installs include a live-generation display in the entrance lobby or main hall and a curriculum pack tied to KS2 Geography, Science and Design & Technology. Pupils can watch real-time generation, lifetime kWh and CO2 saved, and several schools run a "green-energy ambassador" scheme off the data. For a governing body weighing scarce capital against teaching priorities, the fact that the roof also becomes a lesson is very often what tips the decision — and it is a point Ofsted has been known to note positively where sustainability leadership is genuine. Some primaries have pupils film a time-lapse of the install itself for a D&T project, which turns the one genuinely disruptive week into a piece of learning.

Our school holidays are when the panels generate most — won't we just waste it?

That is the real primary paradox, and we design around it rather than gloss over it. The summer surplus is never truly wasted: under the Smart Export Guarantee it still earns 4 to 15p per kWh. On a primary, though, a small battery usually earns its keep by moving that July and August generation into September term-time use. And because Salix finance is interest-free, the overall maths works even at modest self-consumption. We model both the battery and battery-free cases from your actual meter data and show you which wins, in pounds, on your building.

We're a small school on a single-phase supply — can we even have solar?

Yes, but the supply sets the ceiling. A 60 to 100 amp single-phase supply caps practical PV at roughly 13 to 17 kW without a grid upgrade. For many small primaries that is still a worthwhile 10 to 15 kW array that meaningfully cuts the daytime bill. Where you want more, a three-phase upgrade unlocks it — we quote the upgrade transparently as part of the feasibility study so you can decide with the full picture, not after committing.

Will the installation disrupt the children?

No. We schedule the noisy phases for the holidays and keep pupils away from any working area with escorted, DBS-cleared crews. Commissioning is a one to two day event we time for an INSET day or Friday evening. The disruption a primary actually experiences is a fraction of what parents fear, precisely because we design the programme around the school calendar rather than our own.

How do you protect our roof, and what happens after commissioning?

A full structural survey precedes any quote, because a 1960s flat-roofed primary behaves very differently from a Victorian pitched original, and we use roof-warranty-compatible fixings on every project so your existing roof guarantee is preserved. The install carries a ten-year insurance-backed workmanship warranty. Afterwards a small primary system is close to maintenance-free: panels are cleaned by rainfall on a pitched roof, inverters are monitored remotely, and we flag any drop in output before it costs you generation. For a primary running its system for 25-plus years, that long tail of quiet, reliable saving is the real prize behind the headline payback figure.

Ready to see the numbers for your building? Start with a free feasibility study on our quote page, or read how a heavier daytime load changes the economics on our secondary schools page. For the full cost picture, see our school solar cost guide and the funding routes on our grants and funding page.